Overload-indicating apparatus for transformers



T. D. ADAIR, JR

OVERLOAD INDICATING APPARATUS FOR TRANSFORMERS I Deie. 30.1924.

Filed Oct-l 11. 1921 Patented Dec. 30, 1924,

@NETED satin THOMAS DONALD ADAIR, .111, 0'35 DOBCHESFI'ER,MASSACHUSETTS, ASSIGNUR, BY MESNE ASSIGNMENTS, T0 LEONARD L. ELDEN ANDDAVID S. BOYDEN. BOTH OF BROOKLINE, MASSACHUSETTS.

OVERLOAD-INDIGATING APPARATUS FOR TRANSFORMERS.

Application filed Getober 11, 1921. Serial No. 507,029.

T 0 all whom it may concern.

Be it known that I, THOMAS DONALD ADAIR, Jr., a citizen of the UnitedStates, residing at Dorchester, in the county of Suffolk and State ofMassachusetts, have invented certain new and useful Improvements inOverload-Indicating Apparatus for Transformers; and I do hereby declarethe following to be a full, clear, and exact description of theinvention, such as will enable others skilled in the art to which itappertains to make and use the same.

The present invention relates to an improvement in overload indicatingapparatus for transformers, and more particularly to semaphores for usein connection with such apparatus.

In the transformer disclosed in the application filed by the presentinventor April 8, 1921, Serial No. L595? 4, the semaphore is enclosedwithin a semaphore box having a window on one side. When the semaphoredrops, it is exhibited at the window. In practice, in order to renderthe semaphore clearly visible and distinguishable, it is painted white.Upon the occurrence of transformer overload, the white was exposed toview by the dropping of the semaphore behind the window.- When thetransformer provided with this overload indicating apparatus was mountedin its usual position on a pole, it was discovered that when viewedagainst light clouds or blue sky, the white semaphore wasindistinguishable from the black semaphore box or from the blackappearance of the window before the semaphore fell. It was also observedthat the i'efiection of the glass in certain positions of sun or cloudmade it appear as if the white semaphore was in overload indicatingposition.

It was attempted to overcome this ditlioulty by providing the semaphorebox with a large bonnet to cut oil reflected light, but this wasineffective because the window was so shaded that with a strong lightbackground it always appeared black,

It was next attempted to overcome the difficulty by striping the whitesemaphore with black, but this was ineii'ective because it wasimpossible for the eye to distinguish the black from the white against abrilliantly illuminated background such as a white cloud or blue sky.

It was next attempted to secure visible indication by providing thesemaphore box with two aligned windows at the top of the box, andpainting the semaphore black. This construction made it possible clearlyto distinguish the dropping of the signal by reason of transmittedlight, but against a dark background the opening appeared black, and insuch case it was impossible to determine whether the semaphore was setor dropped.

Remembering that the signal of said application was visible against ablack background, the present construction was pro duced in whichaperforated screen was provided in the box between the two windows. Whenthe semaphore fell, the perforation would permit the passage of lightthrough the box, and render the signal visible against a white or highlyilluminated background, the screen, being painted white, becomingvisible against a dark background.

So the construction of the present invention was arrived at, in which asignal is visible both against a highly illuminated background oragainst a dark background. With this object in view, the presentinvention consists in the overload indicating apparatus hereinafterdescribed and particularly defined in the claims.

In the accompanying drawings illustrating the preferred form of theinvention, Fig. 1 is a front view of the signal box with the-semaphoreset; Fig. 2 is a front view of thebox with the semaphore tripped; Fig. 3is a sectional elevation of the box; Fig. 4 is a transverse sectionalelevation of the box.

The overload indicating apparatus for transformer as illustrated in thedrawings, comprises a semaphore 19 operated by mechanism responsive tothe overload conditions of the transformer coils, comprising preferablya heat responsive element like that described in said application, whichis connected to a rotatable spindle 25, journaled in a cross bar 27within the semaphore box 28. mounted upon the upper end of a dependingboss 29, having a threaded portion adapted to be extended through a holein the cover of the transformer, upon which a nut which is thereafterscrewed to clamp the boss to the cover. Variations in temperature of thecoil in the transformer operate through the expansion or contraction ofthe heat responsive coil or spiral to cause rotation of the rotatablespindle 25. The semaphore box 28 is provided with two windows 30, S1, atthe top of the box on opposite sides. The window 30 may be called thefront window, and the window 31 the back window. The windows are glazed.Close to the front window the semaphore 19 is supported to slide onvertical rods 32, and normally held in raised position and permitted tofall when the temperature of the oil hath reaches a point correspondingto an overload condition upon the transformer coils. The semaphore 19 issupported in its raised position by a resilient leaf spring 33, securedat its upper ends to the semaphore 19, having its lower end resting uponthe upper surface of a horizontal segmental disk 35 secured to the upperend of the rotatable spindle 25. This disk 35 is provided with a notch.through which the supporting" spring 33 is permitted to pass when thedisk is rotated to bring the notch under the spring as in theconstruction of said application. The scma phore box 28 is provided witha screen 40. having a cut away portion 41. The screen is painted white,and the white screen is disclosed to view through the front window whenthe semaphore 19 drops. The screen is integral with the cross-bar '27 bywhich it is mounted upon the posts 42 and 43, rising from the base orbottom 44 of the semaphore box. The upper end of the screen 40 isprovided with a flange 45. in which are secured the upper ends of thesemaphore guide rods 32. The front side of the semaphore 19, that is tosay. the side to ward the front window 30, is painted black like theoutside of the semaphore box, and

when it is in set position. that is. in its raised position, as shown inFig. 4, it prevents the transmission of light through the box. After thesemaphore is dropped. it is adapted to be lifted by the lifter lever 50.actuated by a push pin 51, the lever being pivoted at 52 in the post 43.The top of the push pin engages the under side of the lifter lever '50,and is adapted to raise it when pressure is exerted upon the push pin.The lifter lever 50 has a transversely extended end or tip 53, whichengages the under side of the sem p r The overload indicating apparatusmounted on its transformer on the pole may have any sort of backgroundagainst which the inspector is required to view it. Thus, the inspectormay find on one semaphore that it has to be observed looking at italmost directly at the sun, or with a blue sky or white cloudbackground, and in such case the light transmitted through the opening41 in the screen will clearly indicate that the semaphore has dropped.Or, failure of light to be visible through the opening 41 will indicatethat the semaphore has not dropped, and that the transformer has notbeen subjected to an overload. On the other hand, if the semaphore isobserved against a dark background, the portions of the screen40 visiblethrough the window 30 will appear white against such dark background,as, for example, a building, or tree, and the indication in such casewill be equally dis; tinguishable and legible.

Having thus described the invention, what is claimed is:

1. Overload indicating apparatus for transformers having, incombination, a semaphore, a semphore box provided with windows onopposite sides of the semaphore, and a screen in the box covering aportion of the area of the window, permitting, upon the fall of thesemaphore, the transmission of light from a light background, and beingitself visible against a dark background 2. Overload indicatingapparatus for transformers having, in combination. a semaphore, a screenhaving a cut away portion, said screen being covered when the semaphoreis in set position, and uncovered when the semaphore indicates overloadcondition, the screen being colored to contrast with a dark background,and to provide for the transmission of light through the cut awayportion so as to be visible against a light background.

3. An indicating device having, in combination, a screen visible againsta dark background and adapted to transmit light from a light background,and a semaphore adapted to be normally set to cover the screen.

4. An indicating device having, in combination, a screen having aportion visible against a dark background and a portion transmittinglight from a light background. a semaphore, a member for normallymaintaining the semaphore in position to cover the screen, and means foractuating the member to allow the semaphore to move and uncover thescreen.

5. Overload indicating apparatus for transformers having, incombination. a semaphore box, a semaphore,'the box being provided withaligned windows, the portion of the semaphore exposed at the window whenthe semaphore is in set position being dark colored, and a portion ofthe apparatus exposed at the Window when the semaphore is tripped beinglight colored so that when the semaphore is tripped, indicating overloadcondition, a passage for light through the box is provided by thealigned Windows and a light colored area is a light background, and thelight colored portion may be visible against a dark background.

T. DONALD ADAIR, JR.

